Category : Files from Magazines
Archive   : VOL10N19.ZIP
Filename : NUMFILES.ASM

;****************************************************************************
; NUMFILES reports the number of SFT entries created to record the state
; of open files, and thus the setting of FILES= in CONFIG.SYS. To create
; NUMFILES.COM from NUMFILES.ASM, type
;
; MASM NUMFILES;
; LINK NUMFILES;
; EXE2BIN NUMFILES NUMFILES.COM
;
; NUMFILES 1.0 Copyright (c) 1991 Jeff Prosise
; First published in PC Magazine, November 12, 1991
;****************************************************************************

code segment
assume cs:code,ds:code
org 100h
begin: jmp short main

msg db "FILES=$"
crlf db 13,10,"$"

;****************************************************************************
; Procedure MAIN
;****************************************************************************

main proc near
xor cx,cx ;Zero SFT entry count
mov ah,52h ;Get address of DOS's List
int 21h ; of Lists
mov di,es:[bx+4] ;Place address of first SFT
mov es,es:[bx+6] ; header in ES:DI
;
; Walk the chain of SFT headers counting the number of entries in each block.
;
mloop: add cx,es:[di+4] ;Add number of SFT entries
; in this block
mov bx,es:[di] ;Place address of next SFT
mov es,es:[di+2] ; header in ES:DI and loop
mov di,bx ; if the offset address
cmp di,0FFFFh ; isn't equal to FFFFh
jne mloop
;
; Display SFT count and exit.
;
mov ah,09h ;Output "FILES="
mov dx,offset msg
int 21h
mov ax,cx ;Transfer count to AX
call bin2asc ;Print it
mov ah,09h ;Output a carriage return/
mov dx,offset crlf ; line feed pair
int 21h
mov ax,4C00h ;Exit with ERRORLEVEL=0
int 21h
main endp

;****************************************************************************
; BIN2ASC converts a binary value in AX to ASCII form and displays it.
;****************************************************************************

bin2asc proc near
mov bx,10 ;Initialize divisor word and
xor cx,cx ; digit counter
b2a1: inc cx ;Increment digit count
xor dx,dx ;Divide by 10
div bx
push dx ;Save remainder on stack
or ax,ax ;Loop until quotient is zero
jnz b2a1
b2a2: pop dx ;Retrieve a digit from stack
add dl,30h ;Convert it to ASCII
mov ah,2 ;Display it
int 21h
loop b2a2 ;Loop until done
ret
bin2asc endp

code ends
end begin